An own goal that Jonathan David thought was his strike midway through the first half, and Manuel Locatelli's 68th-minute spot-kick proved enough for Juve to book their place in the Coppa Italia quarter-finals at the expense of Udinese on Tuesday evening.
Spalletti made wholesale changes to his starting line-up, as expected, with Canada hotshot David taking over as the lone target man from injured Dusan Vlahovic.
Although the 66-year-old head coach arrived at the Turin titans with a reputation for his versatile tactical approach, he surprisingly persisted with his usual 3-4-2-1 formation like Igor Tudor before him.
After six games with these tactics, with the only domination being their Champions League draw at home to Sporting Lisbon, it was widely anticipated that something new would be tried out for this cup tie.
Udinese arrived in Turin, having beaten Parma 2-0 at the weekend. To reach the last Coppa Italia they had seen off Carrarese and Palermo, while Juventus were tackling their first match in the competition.
Following a slow start from both sides, Kenan Yildiz cut in from the left wing and aimed for the bottom right corner on 11 minutes. Shotstopper Razvan Sava had no problem in saving the opening shot of the tie.
After this fluffed chance, the hosts poured forward at every opportunity to delight their vocal supporters inside the Allianz Stadium. They applied the pressure on Kosta Runjaic’s side, notching a fifth corner in as many minutes just before the quarter-of-an-hour mark.
Teenager nets for Bianconeri
Just after Yildiz fired his low shot narrowly wide of the target, the Bianconeri made the breakthough on 23 minutes. Weston McKennie raced down the right wing then picked out goal poacher David to knock the ball into the bottom left corner, which took a deflection off 17-year-old Matteo Palma and was declared an own goal.
On the half-hour mark Udinese appeared to have levelled matters, but Kingsley Ehizibue's dink over keeper Michele Di Gregorio was ruled out for offside.
Juve suffered the same fate as the visitors just three minutes later, with a goal chalked off for offside following a VAR review after David thundered the ball into the roof of the net from a tight angle.
On the stroke of the half-time whistle David should have done better, but was put off by center-back Oumar Solet, with a Sava collecting the tame effort.
It was another midfield battle at the start of the second half, with Udinese's Nicolo Zaniolo and Yildiz off target with their respective efforts.
Locatelli reached Juve milestone
The most interesting aspect early on was bringing on skipper Locatelli just before the hour-mark, who was making his milestone appearance of 200 games for Juventus after replaced injured Federico Gatti.
Locatelli's presence played a pivotal part following a VAR check that confirmed Palma's foul on Juan Cabal, with the Italy international making no mistake by sending his penalty straight down the middle to foil Saba.
Jurgen Ekkelenkamp snatched at his shot from outside the area, sending the ball high and wide of the gaping goalmouth.
A triple substitution from Juventus saw the introduction of Francisco Conceicao, Joao Mario and Lois Openda in a bid to deal with the five changes that had made the visitors look more menacing.
Lennon Miller sent his long-range volley of the left post, but Udinese continued to look lively despite time running out to mount a formidable fightback.
Mario mistake costs Juve
Mario, playing for the first time in six matches, came close to scoring a last-gasp goal but screwed his effort wide from 15 yards. The Portuguese then played a neat one-two with Openda, who buried the ball into the back of the net. Only for a VAR review to rule the strike out as Mario was marginally offside.
The winner of the Atalanta-Genoa Coppa Italia last 16 clash, played tomorrow, will tackle Juventus in Turin on 4 February.
The rest of the Coppa Italia last 16 games will be also played tomorrow, comprising AS Roma vs. Torino, Bologna vs. Parma, Fiorentina vs. Como, Lazio vs. Milan, Inter Milan vs. Venezia and Napoli vs. Cagliari
With Juventus in seventh heaven, and three triumphs on the bounce, the Coppa Italia is their most realistic chance of scooping silverware this term.
JUVENTUS: Di Gregorio - Kelly, Gatti (Locatelli, 56), Kalulu - Cabal (Mario, 74), Koopmeiners, Miretti (Conceicao, 74) Cambiaso - Yildiz (Zhegrove, 84), McKennie - David (Openda, 74). Subs: Adzic, Kostic, Thuram. Rouhi, Scaglia, Felipe, Mangiapoco.